'The Walking Dead' season 4 trailer debuts at Comic-Con

This image released by AMC shows Andrew Lincoln in a scene from "The Walking Dead." (AP Photo/AMC, Gene Page)

AMC premiered an extended trailer for the fourth season of "The Walking Dead" during a Comic-Con panel on Friday.

The clip for the zombie apocalypse series shows "the walkers" encroaching on the survivors at their prison enclave.

"Yeah, the walkers are no threat at all this season," executive producer Gale Anne Hurd jokingly told the crowd.

The clip also teased a catastrophic event inside the prison with multiple deaths. At the end of the trailer, Norman Reedus' Daryl is shown driving a car and overhearing a voice on the radio whispering, "Those who arrive survive."